Heat generated by transistors can limit the speed of modern integrated circuits. Consequently, reducing power dissipation is one of the most important challenges in digital electronics. CMOS field effect transistors typically require voltage supplies greater than 0.5 V to fully switch from on to off. Other logic families, such as ion channels, mechanical relays, and spin-based devices, can operate at lower voltages, and thus with less wasted energy, by exploiting collective phenomena. An example is the orientation of a ferromagnetic domain in a magnetic logic system.